Internal combustion engine piston

ABSTRACT

Internal combustion engine piston, particularly for diesel engines, with a bottom part and a top part which is connected separately thereto by means of an intermediate ring having a forked cross-section.

Unte 1:: States atent 1 1 3,877,351

Barfiss 1 1 Apr. 15, 1975 INTERNAL COMBUSTION ENGINE PISTON 3,385,1755/1968 Meier et a1. 92/220 X [75] Inventor: Eugen Barfiss, Stuttgart,Germany 3 A G FOREIGN PATENTS OR APPLICATIONS [7 1 Mame StuttgartGermany 416,900 7 1925 Germany 123 4135 [22] Filed; June 22, 1973487,377 6/1938 United Kingdom l23/41.35

[21] Appl. No.: 372,642

Primary Examiner-lrwin C. Cohen [30] Foreign Application Priority DataAttorney, Agent, or Firm-William Anthony Drucker June 23, 1972 Germany2230722 [52] U.S. C1. 92/220; 92/186; 92/216 57 ABSTRACT [51] Int. ClF16j 1/00 Field of Search 186, 216, Internal combustion engine piston,particularly for 123/4135 diesel engines, with a bottom part and a toppart which is connected separately thereto by means of an [5 ReferencesCited intermediate ring having a forked cross-section.

UNITED STATES PATENTS 2,266,192 12/1941 Grieshaber 92/220 X 1 Claim, 2Drawing Figures l l 1 Y 1 111 1 11 111 2 a i l I 4 70 l a v (g l I 1 (/1I 1 zqfil X;

\6; \9 1 \K r x INTERNAL COMBUSTION ENGINE PISTON BACKGROUND OF THEINVENTION 1. Field of the Invention The invention relates to an internalcombustion engine piston, particularly for diesel engines, with a bottompart consisting preferably of light metal providing the piston skirt andthe gudgeon pin mounting, and, connected separably thereto, a preferablysteel upper part comprising the piston crown and the ring zone, theupper part being supported by two concentric annular ribs standing outfrom the inside of the piston crown.

2. Description of the Prior Art Such a piston is illustrated in theMotortechnische Zeitung, 31st Year, No. 10, October 1970, on p.415 (FIG.3). With this construction, connection of the bottom part to the toppart is effected by a centrally disposed screw bolt and by expandingbolts which pass through the outer annular ribs and are anchored in thelower part. The inner annular rib is braced on the lower part but is notbolted thereto. Therefore it is capable of additionally supporting thepiston crown which is loaded by the gas forces and of transmitting theseforces to the lower part. However, the inner annular rib can contributenothing towards preventing the outwards arching of the piston crownwhich is observed under heavy loading and which originates fromthe'uneven temperatureand wall thickness conditions.

It would be obvious, then, also to bolt the inner annular rib to thelower part. On the other hand, it must be remembered that the preferablylight metal lower part would then be weakened by additional bores. Infact, a high-strength screw connection between a light metal member anda steel part already presents so many problems that it becomes desirableto minimise the number of connecting elements although spreading thestresses over a plurality of connecting elements is ac knowledged to bevery favourable.

SUMMARY OF THE INVENTION The invention is based on the problem offinding a construction inwhich both the annular ribs projecting from theinside face of the piston crown are rigidly bolted, but in which thelower part nevertheless has to accommodate but few screwed anchorings.

According to the invention, this problem is resolved in that between thelower part and the upper part there is an intermediate ring consistingpreferably of castiron and of bifurcated cross-section, the base part ofwhich is bolted to the lower part of the piston while its two form partsare bolted to the annular ribs projecting from the inside face of thepiston crown.

By reason of the construction according to the invention, the bolting ofboth annular ribs is made possible by a plurality of favourablydistributed screw elements without the lower parts becoming weakened byadditional bores. Furthermore, for connection of the upper part to theintermediate ring, it is possible to use short slender screws so thatthe two annular ribs can remain narrow.

BRIEF DESCRIPTION OF THE DRAWING An example of the embodiment of theobject of the invention is illustrated in the attached drawings, inwhich:

FIG. I is a partial longitudinal section on the line I-I in FIG. 2through a piston according to the invention, and

FIG. 2 is a partial cross-section through the piston, on the line II-IIin FIG. 1

DESCRIPTION OF THE PREFERRED EMBODIMENT The lower part, consisting of analuminium alloy, is generally designated 1 while the upper parts, madefrom steel, is identified by reference numeral 2. It consists of thering zone 3 and a piston crown 4, from the inside face of which projectstwo concentric annular ribs 5, 6. Through the lower part 1 pass strongscrews 7, the ends 8 of which are screwed into the base part 9 of across-sectionally bifurcated intermediate ring 10 made from cast-iron.The fork parts 11, 12 of the bifurcated intermediate ring 10 are boltedto the annular ribs 5, 6 which project from the piston crown 4 by meansof expanding screws 13, 14 which pass through tubes 15, 16 formed on thefork parts ll, 12. The cavity 17 formed by the bifurcated intermediatering 10 and the annular ribs 5, 6 is connected to the coolant circuit bytransfer ports l8, 19.

I- claim:

1. An internal combustion engine piston including a lightweight metallower part comprising the piston skirt, a piston crown connected withthe piston skirt and comprising the upper part of the piston, whichpiston crown is formed from steel, two concentric integral annular ribsprojecting from the inside face of the piston crown, a piston ring zonesurrounding the piston crown, a cross-sectionally Y-shaped bifurcatedannular intermediate ring of cast iron located between the upper andlower piston part, said ring including fork parts mating with saidannular ribs respectively and a base part mating with said lower pistonpart, at least one tube formed on each fork part of the ring, anexpanding screw provided in each tube for bolting the two fork parts ofsaid intermediate ring to the annular ribs, and further screws in asingle circular arrangement located in the piston skirt and connected tosaid base part for bolting the base part of the intermediate ring to thelower part of the piston.

1. An internal combustion engine piston including a lightweight metallower part comprising the piston skirt, a piston crown connected withthe piston skirt and comprising the upper part of the piston, whichpiston crown is formed from steel, two concentric integral annular ribsprojecting from the inside face of the piston crown, a piston ring zonesurrounding the piston crown, a cross-sectionally Y-shaped bifurcatedannular intermediate ring of cast iron located between the upper andlower piston part, said ring including fork parts mating with saidannular ribs respectively and a base part mating with said lower pistonpart, at least one tube formed on each fork part of the ring, anexpanding screw provided in each tube for bolting the two fork parts ofsaid intermediate ring to the annular ribs, and further screws in asingle circular arrangement located in the piston skirt and connected tosaid base part for bolting the base part of the intermediate ring to thelower part of the piston.